This invention relates to the removal of particulate matter and dissolved solids from liquid, and more particularly to a convertible filter unit which can be easily changed to a bag, sleeve, cartridge, tube, or ion exchange structure.
Use of various types of filters to remove particulate solids from liquids is well known in the art. For example, gravity bag filters consisting of bags or pouches of filter fabric have long been used for simple straining operations involving flowing liquid through the bag from inside to outside leaving behind particulate contaminants. Such bag filters are available in a wide variety of both synthetic and natural fibers woven into many types of weaves. Sleeve or supported bag filters are also widely used to remove solid particles from liquids. Water or other liquid is flowed from the outside of the supported bag to the inside, leaving solid particles trapped on the surface of the fabric or other filtering medium.
Cartridge filter units designed either to be disposable after use and replaced or to be cleaned and reused have also found wide use in the art. These filters usually are of a hollow cylindrical configuration formed of woven or compacted fiber, paper, or other porous media. Flow through the filters is usually inwardly through the filtration media, with filtered fluid exiting the system through the hollow filter core.
Ion exchange columns, although operating as a chemical rather than physical process, have many structural and process similarities with filtration equipment. These columns are usually hollow cylinders containing the ion exchange resin material with fluid being directed downwardly through the resin. The ion exchange resin may be designed to remove dissolved cations, anions, or both from a fluid stream.
Each of these systems is generally effective for the particular water treatment process to which it is adapted. However, there may be a wide variety of different process demands facing a user of filtration equipment. These demands may vary from day to day. None of the above discussed types of filtration or ion exchange equipment is versatile enough to be adapted to all, or even a major portion, of the different process demands. For example, if only relatively coarse particles need be filtered at relatively low liquid flow rates, then a bag-type filter will be suitable. If, however, a smaller particle size filter is required, or the liquid stream is highly acidic or basic, or a high rate of filtration is required, a bag-type filter would not be suitable. However, replacing one type of filter with a new piece of equipment every time process requirements change becomes prohibitively expensive.
Accordingly, there is a need in the art for a filtration system which is highly versatile and easily adaptable to a wide variety of process requirements. Additionally, there is a need for a system which can achieve both physical (filtration) and chemical (ion exchange) separations of particulate and dissolved solids from liquid process streams depending on the particular need.